The invention relates to a device for transmitting force according to the type defined in greater detail in the preamble of claim 1.
A force transmission assembly for driving a variable-speed work machine is known from DE 34 41 877 A1. This force transmission assembly consists of a transmission having planetary gearings, wherein a power branch is divided into a mechanical power branch and a hydrodynamic power branch. The hydrodynamic power branch extends via a hydrodynamic converter and is variable in its speed by the converter. It is unified again with the mechanically transmitted power branch in a planetary gearing and thus drives the work machine at the desired speed, although the drive assembly, which drives the force transmission assembly at the input shaft, runs at constant speed. The structure described in the cited German publication having the concentrically running shafts is to be implemented in a comparatively space-saving manner with respect to structures having shafts which do not run concentrically. However, it requires a coupling sleeve or a hollow shaft and also a stationary transmission for splitting the power branches. This makes the structure comparatively heavy and in particular the use of the coupling sleeve having the comparatively large diameter of the ring gear of the planetary gearing makes the structure relatively costly. In addition, a majority of the force transmission assembly must be installed in the interior of this coupling sleeve, whereby the accessibility is very poor in case of damage, for repair purposes, or the like.
Based on this structure, DE 10 2008 034 607 describes a similar structure, which replaces the hollow shaft with coupling shafts extending in parallel to the central axis of the force transmission assembly. The complex, costly, and very heavy coupling sleeve can thus be omitted. However, the structure is still comparatively large and, due to the external parallel transmission shafts, which must be connected via suitable gearings to the main shaft, comparatively complex and requires manifold individual components. This makes the production and the installation costly and complex.
Furthermore, reference is made to drivetrains in the field of automotive technology. Counterrotating converters in combination with planetary gearings are described here. For example, in DE 41 02 493 A1 or EP 2 101 084 A2. The construction is accordingly complex, since the stated object here is entirely different, namely converting a variable input speed in accordance with the requirements in a suitable gear step/transmission ratio. A variably controlled output speed does not play a role here.
The object of the present invention is therefore to specify a device for transmitting force from a drive assembly running at constant speed to a work machine running at variable speed, which is simple, small, light, and also cost-effective to produce and install.
This object is achieved according to the invention by the features mentioned in the characterizing part of claim 1. Further advantageous embodiments and preferred embodiments are described in the subclaims dependent thereon.
The device according to the invention uses, instead of the heretofore typical hydrodynamic synchronized converter, a hydrodynamic counterrotating converter. It is somewhat worse than a synchronized converter with respect to the efficiency, however, it permits a very simple and compact construction of the device. Since only a specific part of the power is transmitted via the hydrodynamic converter and the larger part of the power is directly mechanically transmitted in any case, no noteworthy restriction results from the efficiency disadvantage of the counterrotating converter with respect to a synchronized converter. The device according to the invention can rather be constructed simply and compactly. The possibility of the compact construction results in particular in the direct attachment of both the turbine wheel and also the pump wheel to corresponding elements of the planetary gearing. A direct attachment as defined in the present invention is to be understood to mean a direct mechanical connection without interposed components such as clutches, transmission elements, or the like.
According to one advantageous embodiment of the device according to the invention, it is provided that the first element is the planet carrier of the planetary gearing, while the second element is the sun wheel of the planetary gearing and the third element is the ring gear of the planetary gearing. This structure, in which the ring gear is connected to the output shaft directly or via a further gearing, preferably a spur gearing, and in which the hydrodynamic power branch is introduced via the sun wheel, has the decisive advantage that the planetary gearing can be embodied very compactly as a result of the favorable speeds.
The device thus offers a very compact structure, which can omit a coupling sleeve. In addition, it can omit an additional stationary transmission in the form of planetary gearings and can thus be embodied as very small and compact having a small number of components and accordingly as simple and cost-effective to produce and install. The structure can, according to an advantageous embodiment, be embodied having precisely one planetary gearing, so that further comparatively complex planetary gearings can be omitted.
According to an advantageous embodiment of the device according to the invention, it is further provided that the turbine of the hydrodynamic counterrotating converter is connected via a hollow shaft to the sun wheel of the planetary gearing and the input shaft extending through the hollow shaft is connected on the side facing away from the hydrodynamic counterrotating converter to the planet carrier. This allows a very compact construction, which may be implemented in a very space-saving manner. The hollow shaft according to this structure is of comparatively small diameter in this case and is by far not as cumbersome and complex as the coupling sleeve in the structure according to the prior art, for example.
In a particularly favorable embodiment thereof, it is provided that the ring gear of the planetary gearing is at least indirectly connected to the output shaft on the side facing away from the hydrodynamic counterrotating converter. The construction may also be implemented very simply and compactly, wherein the mounting of the planetary gearing or one of its elements, respectively, can be implemented such that no or no noteworthy axial forces affect the elements of the planetary gearing. In a corresponding advantageous refinement, it can therefore be provided that the elements of the planetary gearing are embodied as singly helically geared.
Further advantageous embodiments of the device according to the invention additionally result from the remaining dependent subclaims and will be clear on the basis of the exemplary embodiment, which is described in greater detail hereafter with reference to the figures.